I think Geocaching is very useful.

Geocaching is use 'GPS' for find something or some where.

And

The Global Positioning System (GPS) is a space-based global system.

that provides reliable location and time information in all weather

and at all times and anywhere on or near the Earth when and where there is an unobstructed line of sight to four or more GPS satellites.

It is maintained by the Unite states government and is freely accessible by anyone with a GPS receiver.

GPS was created and realized by the DOD and was originally run with 24 satellites.

It was established in 1973 to overcome the limitations of previous navigation systems.

We went to the Pigeon Mountain on foot at 2010/07/27.

I was in B2 group.

There were 4 students in my group.

I didn't know them well.

I found many stickers.

When i found stickers i was so happy!

And i found 4 containers.

It was so funny time.^O^